Fabrication of polyaniline/TiO2 heterojunction structure using plasma enhanced polymerization technique

The work reports on the fabrication of a p–n heterojunction structure comprised of polyaniline (PANI) and TiO2 nanoparticles. PANI was deposited by plasma enhanced polymerization on TiO2 thin film substrates. The structural and the crystalline properties demonstrated the coherence and the substantive interaction of the plasma polymerized PANI molecules with the TiO2 nanoparticle thin film. The UV–Vis studies of PANI/TiO2 thin film supported the internalization of PANI with TiO2 nanoparticles due to π–π∗π–π∗ transition of the phenyl rings with the lone pair electrons (ē) of the nitrogen atom present in the PANI molecules. The II–VV characteristics of the PANI/TiO2 heterojunction structure were obtained in the forward and the reverse biased at applied voltage ranging from −1 V to +1 V with a scan rate of 2 mV/s. The proficient current in the PANI/TiO2 heterojunction structure was attributed to the well penetration of PANI molecules into the pores of the TiO2 nanoparticle thin film. The II–VV characteristics ensured an efficient charge movement at the junction of PANI/TiO2 interface and thus, behaved as a typical ohmic system.